Question

Recently I've learned of Wubi, a way to install Ubuntu right from Windows.

Besides installing from Windows, I would like to know key differences between a regular "alongside Windows" or Dual-boot Ubuntu installation and one done with Wubi. Are there any disadvantages (for example a performance penalty) or incompatibilities I should look out for when using Wubi?

9 Answers
9

You can expect disk performance to be a bit lower (bouncing through NTFS isn't exactly ideal), and you're still somewhat at the mercy of Windows. If your Windows install goes pear-shaped, you may lose access to your Wubi install, too. The reliance on NTFS would also give me heartburn in general, but that by itself probably won't be a serious reliability problem.

Other than that, I can't think of anything that should be different. If you do find a problem, report a bug! :)

There is one other catch noted on the Wubi FAQ in addition to performance/reliability: Hibernation isn't supported.

(I'll note for the record, however, that even with native installs, I've rarely had reliable suspend or hibernation support in any Linux distribution, including Ubuntu.)

if I install wubi on another partition, when losing windows, I just have to install another one.
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silentbangAug 6 '11 at 0:38

I run Ubuntu 10.04 on my AspireOne netbook and use Suspend pretty much every day, and hardly ever shutdown or reboot. Occasionally the wifi will freak out on resume, but not often and in general I find that the suspend / resume functionality works pretty well.
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Robert S. BarnesDec 14 '11 at 11:21

Actually, Ubuntu does have disk swap and it does have a separate disk partition. And so what if it doesn't! Just go into the command line interface in windows and type
diskpart disk_partition_name
I've even seen it have it. If I go into my disk partitions right now and see, I'll see:

And then I see my hard drive partition.
If you install Ubuntu and go into computer management\storage\disk management and look at your partitions, you will see your partitions and you may see Ubuntu there. You can even

For the most part they are the same. Hibernation is not supported. Your performance bottlenecks may be different since the filesystem is compressed (with a fast processor and slow disk your performance might actually be slightly better). You'll be at the mercy of the fragmentation of the underlying NTFS system, so be sure to thoroughly defragment before installing (Ultradefrag (available on sourceforge) does a much more thorough job than the built-in Windows one).

The one gotcha that I have noticed in all the versions I have used is that power failures while running the Ubuntu install quite often leave Ubuntu in an unbootable state. Fixing it, while possible, is something of a pain. As such, if the purpose behind using wubi is to test and see if you can use Ubuntu for your purposes, and the machine on which you are using it has two or more processor cores, I usually recommend VirtualBox instead as being more reliable and more useful for testing since you can switch back and forth instantly instead of having to reboot.

Phoronix published a decent article on the performance impact of running Ubuntu as a WUBI installation.

The most interesting results are from the disk and database benchmarks where the WUBI installation appears to outperform the standard installation, sometimes by a factor of 24(!) It's a pity that the article doesn't attempt to explain this huge performance delta, but one of the commenters in the article's discussion offers up a plausible explanation. The relevant quote is reproduced below:

When linux is installed "on top" of something, writes requiring a fsync (sync to disk) are cached instead of being performed.
this operation is very slow, and used for every single transaction in databases such as postgresql or sqlite unless disabled (and it's not)

Don't run mission critical databases on a WUBI installation, as fsync does not flush the data to the disk and still leaves it cached. This dramatically improves performance at the expense of reliability. This shouldn't impact normal apps.

The biggest advantage of WUBI is that you can easily uninstall Ubuntu if you finally decide that it's not for you.

One big advantage to Wubi to a new user looking to test, is that it installs, un-installs like any other Windows program through the add/remove programs... But runs much better then running it off a live disc... Kinda like the best of both worlds...

Obviously the best long term solution is dual booting, if you have the disc space, but if you are just wanting to test it out, see if it runs well on your computer or install it for short term then Wubi will fit your needs...

if you install ubuntu on windows file system many of the linux included software will not apply including so many file system check tools and permissions too so you will not really have a secure system as i know linux does not support windows file system NTFS so permissions like read write and execute will be limited. but for a regular user who want to test ubuntu he will not see any major differences

Compared with a regular installation, a Wubi installation faces some limitations. Hibernation is not supported and the filesystem is more vulnerable to hard reboots. Also, if the Windows drive is unmounted uncleanly (most commonly because of a Windows crash), Ubuntu will not be able to mount the Windows drive and boot until Windows has successfully booted and shut down. If the Windows system cannot be booted after the crash, the user also cannot boot Ubuntu.

Performance related to hard-disk access is also slightly slower, more so if the disk image file is fragmented, on a Wubi install compared to a normal one.

I have installed ubuntu by wubi in a trial period. If in this period i don't figure out critical disadvantages then i completely move to ubuntu and install it normally. It's my vision of wubi.
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AbonecApr 29 '11 at 20:42

Not key, but tiny difference out of the box without any modification, a Wubi install will leave windows as the default boot (so if you hit power and walk away you get Windows), a normal install will default to Ubuntu. Because of this and the issue noted above, I usually look at it this way.
Windows user who wants to play with Ubuntu on occasion or see how they like it on more than a LiveCD basis, I recommend Wubi.
Someone who is tired of Windows but may need to access some old program for something important at some random time in the future, then shrink the Windows partition and make it an Ubuntu box.